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An impoundment is a structure within inland waters that can permanently or temporarily change the water level or flow. This includes:

• dams
• weirs
• fish passes
• hydropower turbines
• sluices
• penstocks
• culverts
• lock gates
• retaining walls
• flumes
• reservoir embankments
• temporary diversions during construction work

You must have an impounding licence before you start work on building a new impoundment structure, even in an emergency.

If an existing structure does not currently have an impounding licence, you must get one before you start work to alter or remove the structure.

There are some situations where you may not need an impounding licence.

Exemptions

You do not need an impounding licence if your activity is exempt.

The exemptions are:

• works constructed without a licence before 1 April 2006, except where a notice is served by the Environment Agency requiring application for a licence
• where a public authority that manages or owns waterways or harbours constructs any new impoundment, alters an existing impoundment or obstructs or impedes the flow of inland waters while exercising its powers or undertaking its duties
• where the impoundment is authorised by a drought order or drought permit
• where structures and works are authorised by legislation (for example an act of Parliament)
• works constructed or altered by a water company that is authorised by a development control order
• where the Environment Agency serves notice requiring impoundment only for the purpose of screening or passage for eels

Low risk impounding activities

Some impounding activities have a low impact on the environment and other water users.

Check if you can comply with the conditions in the Environment Agencys regulatory position statement Low risk impounding activities: RPS 302. You will not normally need to apply for an impounding licence if you can.

Apply for a licence to impound water

Find out how toapply for a licence to impound water.

Other permissions you may need

You may also need to apply to the Environment Agency for an environmental permit for a flood risk activity when you build in, over or next to main rivers. For rivers and watercourses that are not main rivers you must apply to your lead local flood authority for consent.

If you want to abstract (take) water, check if you need an licence to abstract water.

Get advice

If you are not sure if your proposal needs an impounding licence, you can get advice using the Environment Agencys enhanced pre-application service.